Laminated film

ABSTRACT

The invention provides a laminated film that has, when being formed as a gas-barrier laminated film provided with an inorganic thin film layer, excellent oxygen gas barrier properties and adhesion between respective layers under normal conditions and, even after being subjected to a moist heat treatment, has good adhesion even when subjected to processing such as printing or lamination The laminated film has (a) a covering layer on at least one surface of a substrate film, wherein the covering layer contains a covering layer resin composition with a resin having an oxazoline group as a constituent component, (b) an inorganic thin film layer on the covering layer, and (c) a protective layer that has a urethane resin and an arithmetic mean roughness of 0.5-2.0 nm in a 2-μm square and is on the inorganic thin film layer. The laminated film has a surface hardness of 350-700 N/mm2.

TECHNICAL FIELD

The present invention relates to a laminated film used in a packagingfield for foods, medicines, industrial products and others. Theinvention relates particularly to a laminated film which can express agood gas barrier performance, adhesion, printing performance andheat-moisture resistance as a result of controlling the physicalproperties on the film surface when the film is rendered a gas barrierlaminated film having an inorganic thin-film layer.

BACKGROUND ART

Packaging materials used for foods, medicines and others are required tohave a property of blocking gases such as oxygen and water vapor, thatis, a gas barrier performance to restrain proteins, and fats and oilsfrom being oxidized, keep taste and freshness, and maintain efficaciesof the medicines. Gas barrier materials used in electronic devices orelectronic parts, such as solar batteries and organic ELs, are requiredto have a higher gas barrier performance than the packaging materialsfor foods and others.

In the use of food which is required to block various gases, such aswater vapor and oxygen, in general, a gas barrier laminated body hasbeen hitherto used which has a substrate film made of a plasticmaterial, and a metallic thin film or inorganic thin film on a surfaceof the substrate film, the former thin film being made of, for example,aluminum, or the latter thin film being made of an inorganic oxides suchas silicon oxide or aluminum oxide. Out of such laminated bodies, alaminated body has widely been used in which a thin film of an inorganicoxide made of, for example, silicon oxide, aluminum oxide or a mixtureof these oxides (inorganic thin-film layer) is formed since thelaminated body is transparent to allow to check a content in thelaminated body.

However, this gas barrier laminated body has a problem that theinorganic thin-film layer is physically damaged by flexing-load in astep of post-processing the laminated body, such as a printing,laminating or bag-manufacturing step, and in a laminated-bodytransporting/circulating step, so that the laminated body isdeteriorated in gas barrier performance. When the inorganic thin-filmlayer is once damaged in the processing step, it is feared that thelaminated body is largely damaged in gas barrier performance byundergoing a subsequent heat-moisture treatment such asboiling/retorting treatment. Moreover, a film in which interlayeradhesion is poor between a vapor-deposited layer and a resin contactingthis layer undergoes exfoliation by flexing-load. Consequently, problemsare caused that the film is deteriorated in barrier performance, and acontent therein leaks out.

Against the problems, as a method for improving a deterioration of a gasbarrier laminated body in which an inorganic thin-film layer is formed,the following method has been suggested: a method of locating a coatinglayer made of an aqueous polyurethane resin or a polyester resin thatmay be of various types, or a mixture of a polyurethane and a polyester(for example, Patent Document 1) between a polyester substrate film andan inorganic thin-film layer formed by, for example, vapor deposition.Furthermore, a report has been made about a technique of laying acoating layer made of an oxazoline-group-containing water-solublepolymer to improve the coating layer in water resistance under aheat-moisture condition (see, for example, Patent Document 2). Thelaying of the coating layer between the substrate film and the inorganicthin film can be continuously performed while a film of the substrate isformed. Thus, it can be expected that the laying makes costs far lowerthan the formation of a protective layer on the inorganic thin film.However, in this structure, the resultant laminated body is notsufficient in gas barrier performance since the coating itself has nogas barrier performance so that only the inorganic thin-film layercontributes mainly to the gas barrier performance of the laminated body.Thus, this structure has a problem that the laminated body is notsufficient in gas barrier performance.

Against this problem, an attempt has been made in which a protectivelayer having gas barrier performance is further laid on theabove-mentioned inorganic thin film. Suggested has been, for example, amethod of coating the upper of an inorganic film with a water-solublepolymer, an inorganic lamellar compound, and a metal alkoxide orhydrolyzate thereof, and then using a sol-gel method to produce, on theinorganic thin film, a complex of an inorganic substance containing theinorganic lamellar compound, and the water-soluble polymer. According tothis method, the resultant laminated body shows excellent propertiesalso after subjected to a heat-moisture treatment. However, the liquidsupplied for the coating is low in stability to cause the followingproblems: the laminated body is varied in properties between thestarting time of the coating and the ending time thereof (for example,when the laminated body is made into a roll film to be industriallycirculated, the laminated body is varied therein between an outercircumferential portion of the roll and an inner circumferentialportion); the film is varied in properties in the width directionthereof by a slight difference in drying- orthermal-treatment-temperature of the film in this direction; and suchfilms are largely varied in quality in accordance with the environmentat the producing time of the films. Furthermore, the film obtained bythe coating by the sol-gel method is poor in flexibility. Thus, it ispointed out as a problem that when the film is flexed or impacted,pinholes or defects are easily generated to lower the film in gasbarrier performance. Also, a film coated by the sol-gel method has a lowsurface wettability and hence tends to become a flat and smooth surface,thereby raising a problem in that a sufficient adhesion may not beobtained on the ink at the time of printing process or on the adhesiveat the time of lamination process. In order to solve this problem, thereis a need for measures such as changing the components of the ink oradhesive to have a structure that is more likely to adhere to thesol-gel layer, extending the aging time after the application, andincreasing the adhesive film thickness, thereby imposing a restrictionon the productivity at the time of processing or economy (costs).

Under such a situation, in a coating method without using any sol-gelmethod or the like, that is, in a coating method in which a resin ismainly used and at the time of coating with the resin a crosslinkingreaction is involved in the coating, it is desired to make animprovement capable of forming a layer of the resin on an inorganicthin-film layer. Examples of a gas barrier laminated body in which suchan improvement is made include a gas barrier laminated body in which theupper of an inorganic thin film is coated with a resin layer containingan inorganic lamellar compound of a specific particle size and aspectratio; a gas barrier laminated body in which the upper of an inorganicthin film is coated with a barrier resin containing a silane couplingagent; and a laminated body in which the upper of an inorganic thin filmis coated with a m-xylylene-group-containing polyurethane (see, forexample, Patent Document 3).

However, in the current circumstance, the above-mentioned methods areeach incapable of yielding a gas barrier film which is excellent inproduction stability and economy when produced, which can maintain agood barrier performance and adhesion even after being subjected to asevere heat-moisture treatment, and which also has a sufficient transferperformance and adhesion to an ink at the time of printing and to anadhesive at the time of lamination.

PRIOR ART DOCUMENTS Patent Document

Patent Document 1: JP-A-02-50837

Patent Document 2: Japanese Patent No. 5560708

Patent Document 3: Japanese Patent No. 4524463

Patent Document 4: JP-A-11-179836

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Patent Document 2 described above aims particularly to maintain theretort barrier performance of the laminated film; thus, noinvestigations are made about an improvement thereof in gas barrierperformance before a treatment is applied to the laminated body. AboutPatent Document 3, an investigation is made about the temperaturedependency of the oxygen permeability of the laminated body. Theseproperties each show a good value. However, investigations are not madeabout the gas barrier performance or adhesion of the laminated filmafter a severe heat-moisture treatment, such as retort/boiling.

In light of such problems in the prior art, the present invention hasbeen made. An object thereof is to provide a laminated film which hasthe following advantages when the film is rendered a gas barrierlaminated film having an inorganic thin-film layer: in the state thatthe film is kept in an ordinary state, and also after the film issubjected to a heat-moisture treatment, the laminated film is excellentin oxygen gas barrier performance and in adhesion between its layers;has a good adhesion when processing such as printing or lamination iscarried out; is easily produced; and is also excellent in economy.

Means for Solving the Problems

The present inventors have found out that: a laminated film is formed tohave a structure in which an inorganic thin-film layer is sandwichedbetween a specific coating layer and a specific barrier protective layerthat are each excellent in flexibility and adhesion; and this structureallows to improve the laminated film in gas barrier performance before atreatment is applied thereto, and to maintain the barrier performance,and adhesion also after the film is subjected to a severe heat-moisturetreatment. Thus, the present invention has been accomplished.

Accordingly, the present invention has an aspect or embodiments asdescried below.

(1) A laminated film comprising a substrate film and a coating layerthat is disposed on/over at least one surface of the substrate film; thecoating layer comprising a resin composition for coating layer,comprising, as a constituent component, a resin having an oxazolinegroup; the laminated film having an inorganic thin-film layer on/overthe coating layer, and further having a protective layer that has aurethane resin on/over the inorganic thin-film layer; the protectivelayer of the laminated film having a surface hardness of 350 to 700N/mm²; and the protective layer having an arithmetic mean roughness of0.5 to 2.0 nm in a 2-μm square.

(2) The laminated film according to item (1), wherein the protectivelayer contains an aromatic or aromatic-aliphatic component.

(3) The laminated film according to item (1) or (2), wherein theprotective layer contains a m-xylylene diisocyanate component.

(4) The laminated film according to any one of items (1) to (3), whereinan oxazoline-group-containing resin in the resin composition for coatinglayer, contains an oxazoline group amount of 5.1 to 9.0 mmol/g.

(5) The laminated film according to any one of items (1) to (4), whereinthe coating layer comprises therein an acrylic resin having an acidvalue of 10 mgKOH/g or less.

(6) The laminated film according to any one of items (1) to (5), whereinthe inorganic thin-film layer is a layer of a complex oxide of siliconoxide and aluminum oxide.

Effect of the Invention

The present invention allows to provide a laminated film which has thefollowing advantages when this film is rendered a gas barrier laminatedfilm having an inorganic thin-film layer: of course in the state thatthe film is kept in an ordinary state, or even after the film issubjected to a severe heat-moisture treatment such as a retortingtreatment, the laminated film maintains an excellent gas barrierperformance, and expresses a good laminate strength (adhesion) that doesnot generate any delamination. Additionally, even in a processing stepsuch as printing or lamination, the laminated film of the presentinvention can ensure a stable product quality regardless of whichmaterial is selected and under a wide range of production conditions, sothat it is possible to provide a gas barrier film which is excellent inboth of economy and production stability, and has homogeneousproperties.

MODE FOR CARRYING OUT THE INVENTION

The laminated film of the present invention is a film having a plasticsubstrate film; and a coating layer, an inorganic thin-film layer, and aprotective layer on/over at least one surface of this substrate film.Initially, a description will be made about the plastic substrate film.Next, a description will be made about the coating layer, the inorganicthin-film layer and other layers that are each laminated on/over thissubstrate film.

[Substrate Film]

The substrate film used in the present invention (hereinafter referredto also as the “substrate film”) may be, for example, a film yielded bymelt-extruding a plastic, optionally drawing the extruded film in thelongitudinal direction and/or width direction thereof, and then coolingand thermally fixing the film. Examples of the plastic includepolyamides such as represented by nylon 4.6, nylon 6, nylon 6.6, andnylon 12; polyesters such as represented by polyethylene terephthalate,polybutylene terephthalate, and polyethylene-2,6-naphthalate;polyolefins such as represented by polyethylene, polypropylene, andpolybutene; and further polyvinyl chloride, polyvinylidene chloride,polyvinyl alcohol, wholly aromatic polyamide, polyamideimide, polyimide,polyetherimide, polysulfone, polystyrene, and polylactic acid. Amongthese, polyesters are preferable from the viewpoint of heat resistance,dimension stability and transparency, and particularly preferably,polyethylene terephthalate, or a copolymer yielded by copolymerizingpolyethylene terephthalate and some other component.

The substrate film may be a substrate film having any film thickness inaccordance with desired mechanical strength, transparency and otherpurposes thereof, and the usage thereof. The film thickness is notparticularly limited. The film thickness is usually recommended to befrom 5 to 250 μm. When the substrate film is used as a packagingmaterial, the thickness is desirably from 10 to 60 μm.

The transparency of the substrate film is not particularly limited. Whenthe substrate film is used as a packaging material for whichtransparency is required, the film desirably has a light raytransmittance of 50% or more.

The substrate film may be a monolayered film made of a single plasticspecies, or a laminated film in which two or more plastic films arelaminated onto each other. When the substrate film is rendered alaminated film, for example, the species of the laminated body, thenumber of the laminated layers, and the laminating method are notparticularly limited. These may be selected at will from known methodsin accordance with a purpose of the film.

As far as the objects of the present invention are not damaged, thesubstrate film may be subjected to a surface treatment such as coronadischarge treatment, glow discharge, flame treatment, or asurface-roughening treatment. Moreover, the substrate film may besubjected to, for example, a known anchor coat treatment, printing ordecoration.

[Coating Layer]

The coating layer in the present invention includes a resin having anoxazoline group. It is particularly preferred that in the coating layer,unreacted ones out of their oxazoline groups are present. Oxazolinegroups are high in affinity with an inorganic thin film, such as a metaloxide. Moreover, when the inorganic thin-film layer is formed, thegroups react with oxygen-deficient moieties of a generated inorganicoxide, or a metal hydroxide, so that the oxazoline groups show a strongadhesion to the inorganic thin-film layer. Additionally, the unreactedoxazoline groups present in the coating layer react with the substratefilm and with a terminal of a carboxylic acid generated by thehydrolysis of the coating layer, so that the groups form crosslinkage.Consequently, the coating layer can keep water resistance.

By causing the unreacted oxazoline group moieties and the reactedcrosslinked moieties to coexist in the coating layer, the coating layerbecomes a film having both of water resistance and flexibility. For thisreason, when flexing-load or the like is applied thereto, stress to theinorganic thin-film layer can be relieved so that this layer can berestrained from being lowered in gas barrier performance.

Also the coating layer made only of a resin having an oxazoline groupcan express heat-moisture treatment resistance. However, when thecoating layer is subjected to a longer-period and higher-temperaturesevere heat-moisture treatment, the inorganic thin-film layer may not beavoided from being damaged by a deformation of the coating layer itselfsince the coating layer itself is somewhat insufficient in cohesiveforce. Thus, in the present invention, it is preferred that the coatinglayer further includes an acrylic resin in order that the coating layercan sufficiently ensure a severer heat-moisture treatment. The inclusionof the acrylic resin makes an improvement of the coating layer itself incohesive force followed by water resistance.

When a urethane resin, particularly, a urethane resin having acarboxylate group is further contained in the resin composition forcoating layer in the present invention, the resultant coating layer canbe made higher in heat-moisture treatment resistance. In other words,when the carboxylic group in the urethane resin is caused to react withthe oxazoline group, the coating layer becomes a layer having theflexibility of the urethane resin while partially crosslinked. Thus,stress relief of the inorganic thin-film can be attained at a higherlevel.

Although the laminated film of the present invention is a laminated bodyhaving the inorganic thin-film layer, the laying of the coating layerallows that the inorganic thin-film layer maintains gas barrierperformance and interlayer adhesion according to the above-mentionedembodiment even after the laminated film is subjected to a heat-moisturetreatment such as retorting.

The following will describe, in detail, constituent components of theresin composition for coating layer, which forms the coating layer.

(Resin (A) Having Oxazoline Group)

The coating layer in the present invention contains a resin having anoxazoline group. This oxazoline-group-having resin is, for example, apolymer having an oxazoline group that is yielded by copolymerizing apolymerizable unsaturated monomer having an oxazoline group and anoptional different polymerizable unsaturated monomer by a method knownin the prior art (for example, solution polymerization or emulsionpolymerization).

Examples of the polymerizable unsaturated monomer having an oxazolinegroup include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline,2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline,2-isopropenyl-4-methyl-2-oxazoline, and2-isopropenyl-5-ethyl-2-oxazoline. These monomers may be used alone orin combination of two or more thereof.

Examples of the different polymerizable unsaturated monomer includemethyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate,butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl(meth)acrylate, lauryl (meth)acrylate, isobornyl (meth)acrylate, andother alkyl or cycloalkyl esters of (meth)acrylic acid that each have 1to 24 carbon atoms; 2-hydroxyethyl (meth)acrylate, hydroxypropyl(meth)acrylate, and other hydroxyalkyl esters of (meth)acrylic acid thateach have 2 to 8 carbon atoms; styrene, vinyltoluene, and other vinylaromatic compounds; (meth)acrylamide,dimethylaminopropyl(meth)acrylamide, dimethylaminoethyl (meth)acrylate,any adduct of glycidyl (meth)acrylate and an amine; polyethylene glycol(meth)acrylate; and N-vinylpyrrolidone, ethylene, butadiene,chloroprene, vinyl propionate, vinyl acetate, and (meth)acrylonitrile.These may be used alone or in combination of two or more thereof.

The oxazoline-group-having resin used in the present invention ispreferably a water-dispersible resin from the viewpoint of improvementsof the resin in compatibility with other resins and wettability and incrosslinking reaction efficiency, an improvement of the coating layer intransparency, and others. In order to render this oxazoline-group-havingresin a water-dispersible resin, it is preferred to incorporate ahydrophilic monomer, as the different polymerizable unsaturated monomer,into the resin-starting monomers.

Examples of the hydrophilic monomer include 2-hydroxyethyl(meth)acrylate, methoxy polyethylene glycol (meth)acrylate, monomerseach having a polyethylene glycol chain, such as a monoester compoundmade from (meth)acrylic acid and polyethylene glycol, 2-aminoethyl(meth)acrylate and salts thereof, (meth)acrylamide,N-methylol(meth)acrylamide, N-(2-hydroxyethyl)(meth)acrylamide,(meth)acrylonitrile, and sodium styrenesulfonate. Out of such monomers,preferred is a monomer having a polyethylene glycol chain, such as amonoester compound made from (meth)acrylic acid and polyethylene glycol(the molecular weight of the introduced polyethylene glycol chain ispreferably from 150 to 700, and is from 150 to 200, particularly, fromthe viewpoint of the water resistance of the laminated film, or ispreferably from 300 to 700 from the viewpoint of the compatibility ofthe monomer with other resins, and the transparency of the coatinglayer).

In the copolymer made from the polymerizable unsaturated monomer havingan oxazoline group and the different polymerizable unsaturated monomer,the composition proportion by mole of this oxazoline-group-havingpolymerizable unsaturated monomer is preferably from 30 to 70% by mole,more preferably from 40 to 65% by mole.

In the oxazoline-group-having resin, the oxazoline group content ispreferably from 5.1 to 9.0 mmol/g, more preferably from 6.0 to 8.0mmol/g. In the prior art, about the use of a resin having an oxazolinegroup in a coating layer, the following example has been reported; anexample in which a resin having an oxazoline group content of about 5.0mmol/g is used (see, for example, Patent Document 4). In the presentinvention, however, a resin having a relatively large oxazoline groupamount is used. This is because the use of the resin having a largeoxazoline group amount allows to form a crosslinked structure in thecoating layer and simultaneously cause some of the oxazoline groups toremain in the coating layer. As a result, this matter contributes to themaintenance of the gas barrier performance of the laminated film, and animprovement thereof in flexing resistance when the film is subjected toheat-moisture treatment. Such oxazoline-group-containing resins arecommercially available as “EPOCROS (registered trademark)” series fromNippon Shokubai America Industries, Inc.

The content proportion of the oxazoline-group-having resin in the entireresin components in the resin composition for coating layer ispreferably from 20 to 60% by mass, more preferably from 25 to 55% bymass, even more preferably from 30 to 50% by mass of the entire resins,the proportion thereof being 100% by mass. If the content proportion ofthe oxazoline-group-having resin is less than 20% by mass, the adhesionwater-resistance based on the oxazoline group tends not to besufficiently exhibited. In the meantime, if the proportion is more than60% by mass, the proportion of the unreacted oxazoline groups is solarge that the coating layer becomes insufficient in cohesive force.Thus, the laminated film is unfavorably lowered in water resistance.

(Acrylic Resin (B))

An acrylic resin may be incorporated into the resin composition forcoating layer to improve the coating layer in water resistance andsolvent resistance. The acrylic resin may be an acrylic resin for whichan alkyl acrylate and/or an alkyl methacrylate (hereinafter thesemonomers may be together referred to as an “alkyl (meth)acrylate”)is/are used as a main component or main components. A specific exampleof the acrylic resin is a water-soluble or water-dispersible resin whichusually contains an alkyl (meth)acrylate in a content proportion from 40to 95% by mole, and optionally contains a copolymerizable vinyl monomercomponent having a functional group in a content proportion usually from5 to 60% by mole. When the content proportion of the alkyl(meth)acrylate in the acrylic resin is set to 40% or more by mole, theresin composition becomes good, particularly, in paintability, and instrength and blocking resistance of the resultant painted film. In themeantime, when the content proportion of the alkyl (meth)acrylate is setto 95% or less by mole and a compound having a specific functional groupis introduced, as a copolymerizable component, into the acrylic resin togive a proportion of 5% or more by mole, the acrylic resin can easily bemade water-soluble or water-dispersible and further this state can bestabilized over a long term to result in improvements of adhesionbetween the coating layer and the substrate film, and the strength,water resistance, solvent resistance and others of the coating layer,these properties being based on reaction inside the coating layer. Thecontent proportion of the alkyl (meth)acrylate ranges preferably from 50to 90% by mole, more preferably from 60 to 85% by mole.

The alkyl group in the alkyl (meth)acrylate is, for example, a methyl,n-propyl, isopropyl, n-butyl, isobutyl, 2-ethylhexyl, lauryl, stearyl,or cyclohexyl group.

Examples of the functional group in the copolymerizable vinyl monomerhaving a functional group include a carboxyl group, an acid anhydridegroup, a sulfonate group or salts thereof, an amide group or analkylolated amide group, an amino group (examples thereof includingsubstituted amino groups), an alkylolated amino group or salts thereof,a hydroxyl group, and an epoxy group. Particularly preferred arecarboxyl, acid anhydride, and epoxy groups. Only one, or two or more ofthese functional groups may be present.

Examples of the compound having a carboxyl group or an acid anhydridegroup, which is usable as the vinyl monomer, include acrylic acid,methacrylic acid, itaconic acid, and maleic acid; alkali metal salts,alkaline earth metal salts, and ammonium salts of these acids; andfurther includes maleic anhydride.

Examples of the compound having a sulfonate group or a salt thereof,which is usable as the vinyl monomer, include vinylsulfonic acid,styrenesulfonic acid, and metal (such as sodium) salts and ammoniumsalts of these sulfonic acids.

Examples of the compound having an amide group or an alkylolated amidegroup, which is usable as the vinyl monomer, include acrylamide,methacrylamide, N-methylmethacrylamide, methylolated acrylamide,methylolated methacrylamide, ureido vinyl ether, β-ureidoisobutyl vinylether, and ureidoethyl acrylate.

Examples of the compound having an amino group, an alkylolated aminogroup or a salt thereof, which is usable as the vinyl monomer, includediethylaminoethyl vinyl ether, 2-aminoethyl vinyl ether, 3-aminopropylvinyl ether, 2-aminobutyl vinyl ether, dimethylaminoethyl methacrylate,and dimethylaminoethyl vinyl ether; compounds each yielded bymethylolating an amino group of any one of these compounds; andcompounds each yielded by making the amino group quaternary by effectof, for example, an alkyl halide, dimethyl sulfate or sultone.

Examples of the compound having a hydroxyl group, which is usable as thevinyl monomer, include β-hydroxyethyl acrylate, β-hydroxyethylmethacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate,β-hydroxy vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinylether, polyethylene glycol monoacrylate, polyethylene glycolmonomethacrylate, polypropylene glycol monoacrylate, and polypropyleneglycol monomethacrylate.

Examples of the compound having an epoxy group, which is usable as thevinyl monomer, include glycidyl acrylate, and glycidyl methacrylate.

Besides the compound having any one of the above-mentioned functionalgroups as the alkyl (meth)acrylate or the vinyl monomer, for example,the following may be incorporated, together with the compound, into theaqueous acrylic resin: acrylonitrile, any styrene compound, butyl vinylether, any mono- or dialkyl ester of maleic acid, any mono- or dialkylester of fumaric acid, any mono- or dialkyl ester of itaconic acid,methyl vinyl ketone, vinyl chloride, vinylidene chloride, vinyl acetate,vinylpyridine, vinylpyrrolidone, or vinyltrimethoxysilane.

The acrylic resin preferably has a carboxyl group and has an acid valueof 10 mgKOH/g or less. The acid value is more preferably 8 mgKOH/g, evenmore preferably 5 mgKOH/g or less. When the acid value is 10 mgKOH/g orless, the resin itself is excellent in water resistance. Consequently,the coating layer can be improved in cohesive force even when notcrosslinked. If the acid value is more than 10 mgKOH/g, the coatinglayer is crosslinked to be improved in strength, but is lowered inflexibility so that stress to the inorganic thin-film layer may beunfavorably increased when the laminated film is subjected to aretorting treatment.

In the resin composition for coating layer, which constitutes thecoating layer, the content proportion of the acrylic resin in the entireresins (for example, the whole of the oxazoline-group-having resin, theacrylic resin, and a urethane resin that will be described later) in thecomposition is preferably from 10 to 60%, more preferably from 15 to55%, even more preferably from 20 to 50% by mass of the entire resin,the proportion thereof being 100% by mass. If the content proportion ofthe acrylic resin is less than 10% by mass, thewater-resistance-improving and solvent-resistance-improving effects maynot be sufficiently exhibited. In the meantime, if the proportion ismore than 60% by mass, the coating layer becomes too hard so that stressload onto the inorganic thin-film layer tends to be increased when thelaminated film is subjected to heat-moisture treatment.

(Urethane Resin (C))

The resin composition constituting the coating layer preferably containsa urethane resin.

The urethane resin is, for example, a water-soluble or water-dispersibleresin yielded by causing a polyhydroxy compound (polyol component) and apolyisocyanate compound to react with each other in a usual way. Theaqueous polyurethane resin is preferably a resin containing a carboxylgroup or a salt thereof since this resin is made high in affinity,particularly, with a water medium. These constituent components of theurethane resin can be specified by, for example, nuclear magneticresonance analysis.

Examples of the polyhydroxy compound, which is a constituent componentof the urethane resin, include polyethylene glycol, polypropyleneglycol, polyethylene/propylene glycol, polytetramethylene glycol,hexamethylene glycol, tetramethylene glycol, 1,5-pentanediol, diethyleneglycol, triethylene glycol, neopentyl glycol, polycaprolactone,polyhexamethylene adipate, polyhexamethylene sebacate,polytetramethylene adipate, polytetramethylene sebacate,trimethylolpropane, trimethylolethane, pentaerythritol, and glycerin.

The polyisocyanate compound, which is a constituent component of theurethane resin, include toluylene diisocyanate (2,4- or 2,6-tolylenediisocyanate, or a mixtures thereof) (TDI), diphenylmethane diisocyanate(4,4′-, 2,4′- or 2,2′-diphenylmethane diisocyanate, or a mixturesthereof) (MDI), and other aromatic diisocyanates; xylylene diisocyanate(XDI), and other aromatic-aliphatic diisocyanates; isophoronediisocyanate (IPDI), 4,4-dicyclohexylmethane diisocyanate,1,3-bis(isocyanatomethyl)cyclohexane, and other cycloaliphaticdiisocyanates; 1,6-hexamethylene diisocyanate (HDI),2,2,4-trimethylhexamethylene diisocyanate, and other aliphaticdiisocyanates; and other polyisocyanates obtained by adding one or moreof these compounds in advance to, for example, trimethylolpropane.

In order to introduce a carboxyl group or a salt thereof to a urethaneresin, it is advisable to use, as a polyol component (polyhydroxycompound), for example, a polyol compound having a carboxyl group suchas dimethylolpropionic acid or diethylolbutanoic acid, introduce thiscompound thereinto as a copolymerizable component, and then neutralizethe system with a salt-forming agent. Specific examples of thesalt-forming agent include ammonia, trimethylamine, triethylamine,triisopropylamine, tri-n-propylamine, tri-n-butylamine, and othertrialkylamines; N-methylmorpholine, N-ethylmorpholine, and other alkylmorpholines; and N-dimethylethanolamine, N-diethylethanolamine, andother N-dialkylalkanolamines. These compounds may be used alone or incombination of two or more thereof.

The urethane resin preferably has a carboxyl group and has an acid valuefrom 10 to 40 mgKOH/g. This resin causes the above-mentioned oxazolinegroup to react with the carboxyl group so that the coating layer canmaintain flexibility while partially crosslinked to attain compatibilitybetween a further improvement in the cohesive force, and stress reliefof the inorganic thin-film. The acid value ranges more preferably from15 to 35 mgKOH/g, even more preferably from 20 to 30 mgKOH/g.

In the resin composition constituting the coating layer when the coatinglayer contains the urethane resin, the content proportion of theurethane resin in the entire resins (for example, the whole of theoxazoline-group-having resin, the acrylic resin, and the urethane resin,which will be detailed later) in the resin composition is preferablyfrom 10 to 60%, more preferably from 15 to 55%, even more preferablyfrom 20 to 50% by mass of the entire resins, the proportion thereofbeing 100% by mass. By incorporating the urethane resin into thecomposition in a proportion in these ranges, the coating layer can beexpected to be improved in water resistance.

In the resin composition for coating layer, the ratio of the carboxylgroup amount [mmol] to the oxazoline group amount [mmol] in thecomposition is preferably 20% or less by mmol, more preferably 15% orless by mmol. If the carboxyl group amount is more than 20% by mmol,crosslinking reaction advances excessively when the coating layer isformed. Thus, a large oxazoline group amount is unfavorably consumed.Consequently, the coating layer is lowered in adhesion to the inorganicthin-film layer and in flexibility of the coating layer so that thelaminated film may be unfavorably damaged in gas barrier performance andadhesion after subjected to heat-moisture treatment.

In the present invention, the adhesion amount of the coating layer ispreferably set into the range of 0.010 to 0.200 g/m². This case allowsto control the coating layer evenly so that the inorganic thin-filmlayer can be densely deposited thereon. Moreover, the coating layeritself is improved in cohesive force to heighten adhesion between anytwo of the inorganic thin-film layer-the coating layer-the substratefilm, so that the coating layer can also be heightened in waterresistance. The adhesion amount of the coating layer is preferably 0.015g/m² or more, more preferably 0.020 g/m² or more, even more preferably0.025 g/m² or more, and is preferably 0.190 g/m² or less, morepreferably 0.180 g/m² or less, even more preferably 0.170 g/m² or less.If the adhesion of the coating layer is more than 0.200 g/m², the insideof the coating layer becomes insufficient in cohesive force, and furtherthe coating layer is also lowered in evenness so that defects aregenerated in the inorganic thin-film layer. Thus, the laminated film maynot sufficiently express gas barrier performance before and aftersubjected to heat-moisture treatment. Furthermore, production costs areincreased to give an economic disadvantage in addition to the decline inthe gas barrier performance. In the meantime, if the film thickness ofthe coating layer is less than 0.010 g/m², the laminated film may notunfavorably gain a sufficient gas barrier performance nor interlayeradhesion.

As far as the present invention is not damaged, various known inorganicor organic additives may be optionally incorporated into the resincomposition for coating layer, examples of the additives including anantistatic agent, a lubricant, and an anti-blocking agent.

The method for forming the coating layer is not particularly limited,and may be a method known in the prior art, for example, a coatingmethod. A preferred method, out of coating methods, is an off-linecoating method or an in-line coating method. In the case of, forexample, an in-line coating method performed in a process of producingthe substrate film, drying and thermal treatment conditions in thecoating depend on the thickness of the resultant coat, and conditionsfor the machine. Preferably, immediately after the coating, theworkpiece is sent, in a direction perpendicular to the coatingdirection, into a drawing step, and the workpiece is dried in apre-heating zone or drawing zone in the drawing step. In such a case,the temperature is usually set into a range preferably from about 50 to250° C.

[Inorganic Thin-Film Layer]

The laminated film of the present invention has an inorganic thin-filmlayer on/over the coating layer.

The inorganic thin-film layer is a thin film including a metal orinorganic oxide. A material that forms the inorganic thin-film layer isnot particularly limited as far as the material is a material that canbe made into a thin film. From the viewpoint of gas barrier performance,the material is preferably an inorganic oxide, such as silicon oxide(silica), aluminum oxide (alumina), or a mixture of silicon oxide andaluminum oxide. Particularly preferred is a complex oxide of siliconoxide and aluminum oxide since the oxide allows to make the thin-filmlayer compatible between flexibility and denseness. About the blendratio between silicon oxide and aluminum oxide in this complex oxide,the metal proportion by mass of Al ranges preferably from 20 to 70%. Ifthe Al concentration is less than 20%, the inorganic thin-film layer maybe lowered in water vapor barrier performance. In the meantime, if theconcentration is more than 70%, the inorganic thin-film layer tends tobe hardened, so that the film is broken in a secondary processing, suchas printing or laminating, to be unfavorably lowered in barrierperformance. Silicon oxide referred to herein is a silicon oxide thatmay be of various types, such as SiO or SiO₂, or any mixture of suchoxides, and aluminum oxide referred to herein is an aluminum oxide thatmay be of various types, such as AlO or Al₂O₃, or any mixture of suchoxides.

The film thickness of the inorganic thin-film layer is usually from 1 to100 nm, preferably from 5 to 50 nm. If the film thickness of theinorganic thin-film layer is less than 1 nm, the layer may not easilygain a satisfactory gas barrier performance. In the meantime, if thefilm thickness is set to more than 100 nm to be made excessively large,a gas-barrier-performance-improving effect corresponding to thethickness is not gained to give disadvantages conversely from theviewpoint of flexing resistance and production costs.

The method for forming the inorganic thin-film layer is not particularlylimited. A known vapor deposition method may be appropriately adopted,examples thereof including physical vapor deposition methods (PVDmethod) such as vacuum vapor deposition, sputtering and ion platingmethods, and a chemical vapor deposition method (CVD method). Thefollowing will describe a typical method for forming the inorganicthin-film layer, giving a silicon-oxide/aluminum-oxide based thin filmas an example. In the case of adopting, for example, a vacuum vapordeposition method, it is preferred to use, as a vapor deposition rawmaterial, for example, a mixture of SiO₂ and Al₂O₃, or a mixture of SiO₂and Al. As the vapor deposition raw material, particles are usuallyused. At this time, the size of the individual particles is desirably asize that does not permit the pressure at the time of the vapordeposition to be changed. The particle size is preferably from 1 to 5mm. For heating the particles, for example, the following manner may beadopted: resistance heating, high frequency induction heating, electronbeam heating or laser heating. As a reactive gas, oxygen, nitrogen,hydrogen, argon, carbon dioxide gas, or water vapor may be introducedinto the reaction system. Reactive vapor deposition using ozoneaddition, ion assist or some other means may also be adopted.Furthermore, any change may be applied also to film-forming conditions,for example, bias is applied to a body which vapor deposition is to beapplied (a laminated film to be supplied for vapor deposition), or thisbody is heated or cooled. Also in the case of adopting a sputtering orCVD method, change may be made about, for example, such a vapordeposition raw material, a reactive gas, bias to a body which vapordeposition is to be applied, and/or heating/cooling.

[Protective Layer]

In the present invention, the laminated film has a protective layeron/over the inorganic thin-film layer. The inorganic thin-film layerlaminated on/over the plastic film is not completely a dense film, andhas dotted microscopic deficient moieties. By applying, onto theinorganic thin-film layer, a specific resin composition for protectinglayer, which will be described later, to form the protecting layer, aresin in the resin composition for protecting layer invades thedeficient moieties of the inorganic thin-film layer to produce anadvantageous effect of stabilizing the gas barrier performance of thelaminated film. Additionally, by using a material having gas barrierperformance in the protecting layer itself, the laminated film is alsolargely improved in gas barrier performance.

In the present invention, the protective layer of the laminated filmpreferably has a surface hardness of 350 to 700 N/mm². This allows thelaminated film to have a hardness needed in exhibiting an adhesionforce, and also to maintain the performance thereof even after theretorting treatment. The surface hardness is preferably 375 N/mm² ormore, more preferably 400 N/mm² or more, even more preferably 420 N/mm²or more, and is preferably 675 N/mm² or less, more preferably 650 N/mm²or less, even more preferably 625 N/mm² or less. When the surfacehardness of the protective layer of the laminated film is more than 700N/mm², the surface is too hard, and the adhesive does not invade at thetime of printing or lamination, thereby lowering the adhesion. On theother hand, when the surface hardness is less than 350 N/mm², thecohesive force of the protective layer is weak, thereby raising a fearthat protection of the inorganic thin-film layer may be insufficient,and further a fear that the pigment in the ink may be buried toaggravate the ink transfer performance (printing outer appearance).

In the present invention, the protective layer preferably has anarithmetic mean roughness of 0.50 to 2.0 nm in a viewing angle of 2-μmsquare. This allows the adhesion to be enhanced by the anchor effect offorming a microscopic surface unevenness while maintaining the evennessof the protective layer. The arithmetic mean roughness is preferably0.60 nm or more, more preferably 0.70 nm or more, even more preferably0.80 nm or more, and is preferably 1.9 nm or less, more preferably 1.8nm or less, even more preferably 1.7 nm or less. When the arithmeticmean roughness is more than 2.0 nm, the surface is too rough, and theevenness of the protective layer also decreases to generate unevennessor defects in the coating outer appearance, thereby possibly leading todecrease in the printing suitability. On the other hand, when thearithmetic mean roughness is less than 0.5 nm, the surface is too flat,and the so-called anchor effect is not obtained, thereby raising a fearthat the adhesion or the ink transfer performance at the time ofprinting may decrease.

In the present invention, the adhesion amount of the protective layer ispreferably set into a range of 0.15 to 0.60 g/m² in order to set thesurface hardness and the arithmetic mean roughness of the protectivelayer to be within the aforementioned predetermined range. This caseallows the adhesion to be enhanced by the anchor effect while decreasingthe coating unevenness or defects by the evenness. Moreover, theprotective layer itself is improved in cohesive force to strengthen theadhesion between the inorganic thin-film layer and the protective layer,so that the laminated film can be heightened in water resistance. Theadhesion amount of the protective layer is preferably 0.17 g/m² or more,more preferably 0.20 g/m² or more, even more preferably 0.23 g/m² ormore, and is preferably 0.57 g/m² or less, more preferably 0.54 g/m² orless, even more preferably 0.51 g/m² or less. If the adhesion amount ofthe protective layer is more than 0.600 g/m², the laminated film isimproved in gas barrier performance but the surface hardness decreases,and the inside of the protective layer is insufficient in cohesiveforce, thereby raising a fear that the adhesion may decrease. Also, thearithmetic mean roughness of the protective layer increases, so that theexternal appearance of the coat undergoes unevenness or defects. Thus,after being subjected to heat-moisture treatment, the laminated film maynot sufficiently exhibit gas barrier performance or adhesion. In themeantime, if the film thickness of the protective layer is less than0.15 g/m², the laminated film may unfavorably gain neither a sufficientgas barrier performance nor interlayer adhesion.

In the present invention, a urethane resin is used as the protectivelayer. Because of the presence of urethane bonding moieties having apolarity, the urethane resin has a good adhesion to the metal oxidelayer, and the resin readily invades the deficient moieties. Also, sincethere are crystalline portions having a high cohesive force by thehydrogen bond between the urethane bonds with each other, a stable gasbarrier performance is obtained. Furthermore, since amorphous portionshaving a high flexibility are also present, the surface hardness can beset to be within the aforementioned predetermined range by controllingthe ratio between the amorphous portions and the crystalline portions.As the urethane resin, a water-dispersible urethane resin having a highpolarity and having a good wettability to the metal oxide layer ispreferable. Also, as the curing type of the resin, a thermosetting resinis preferable from the viewpoint of production stability.

(Urethane Resin (D))

The urethane resin (D) is obtained by causing a polyisocyanate component(E), which will be detailed below, to react with a polyol component (F),which will be detailed later in a usual way. Furthermore, the resultantmay be caused to react with a low molecular weight compound having twoor more active hydrogen atoms, such as a diol component (for example,1,6-hexanediol) or a diamine compound (for example,hexamethylenediamine), as a chain extender. In this way, the chain canalso be extended.

(E) Polyisocyanate Component

Examples of the polyisocyanate component (E), which is usable in thesynthesis of the urethane resin (D), include aromatic polyisocyanates,alicyclic polyisocyanates, and aliphatic polyisocyanates. As thepolyisocyanate compound, a diisocyanate compound is usually used.

Examples of the aromatic diisocyanates include tolylene diisocyanate(2,4- or 2,6-tolylene diisocyanate, or a mixture thereof) (TDI),phenylene diisocyanate (m- or p-phenylene diisocyanate, or a mixturesthereof), 4,4′-diphenyldiisocyanate, 1,5-naphthalene diisocyanate (NDI),diphenylmethane diisocyanate (4,4′-, 2,4′-, or 2,2′-diphenylmethanediisocyanate, or any mixture thereof) (MDI), 4,4′-toluidine diisocyanate(TODI), and 4,4′-diphenyl ether diisocyanate. Examples of thearomatic-aliphaticdiisocyanates include xylylene diisocyanate (1,3- or1,4-xylylene diisocyanate, or a mixture thereof) (XDI),tetramethylxylylene diisocyanate (1,3- or 1,4-tetramethylxylylenediisocyanate, or a mixture thereof) (TMXDI), andω,ω′-diisocyanate-1,4-diethylbenzene.

Examples of the alicyclic diisocyanates include 1,3-cyclopentenediisocyanate, cyclohexane diisocyanate (1,4-cyclohexane diisocyanate,and 1,3-cyclohexane diisocyanate),3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophoronediisocyanate, IPDI), methylenebis(cyclohexyl isocyanate) (4,4′-, 2,4′-or 2,2′-methylenebis(cyclohexyl isocyanate)) (hydrogenated MDI),methylcyclohexane diisocyanate (methyl-2,4-cyclohexane diisocyanate, andmethyl-2,6-cyclohexane diisocyanate), andbis(isocyanatomethyl)cyclohexane (1,3- or1,4-bis(isocyanatomethyl)cyclohexane or a mixture thereof) (hydrogenatedXDI).

Examples of the aliphatic diisocyanates include trimethylenediisocyanate, 1,2-propylene diisocyanate, butylene diisocyanate(tetramethylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylenediisocyanate, 1,3-butylene diisocyanate), hexamethylene diisocyanate,pentamethylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylenediisocyanate, and 2,6-diisocyanatomethyl caffeate.

(G) Polyol Component

As the polyol component (particularly, the diol component), anycomponent is usable which is selected from a range from glycols having alow molecular weight to those having a high molecular weight; however,from the viewpoint of gas barrier performance and the flexibility by theamorphous portions, any one of the following is used: alkylene glycols(such as ethylene glycol, propylene glycol, trimethylene glycol,1,3-butanediol, 1,4-butanediol, pentanediol, hexanediol, neopentylglycol, heptanediol, octanediol, and other linear or branched C₂₋₁₀alkylene glycols); and (poly)oxy C₂₋₄ alkylene glycols (such asdiethylene glycol, triethylene glycol, tetraethylene glycol, anddipropylene glycol), and other low molecular weight glycols. A preferredglycol component is a C₂₋₈ polyol component [for example, a C₂₋₆alkylene glycol (particularly, ethylene glycol, 1,2- or 1,3-propyleneglycol, 1,4-butanediol, 1,6-hexanediol, or 3-methyl-1,5-pentanediol)], adi- or trioxy C₂₋₃ alkylene glycol (such as diethylene glycol,triethylene glycol, or dipropylene glycol). A particularly preferreddiol component is a C₂₋₈ alkylene glycol (especially a C₂₋₆ alkyleneglycol).

These diol components may be used alone or in combination of two or morethereof. As the need arises, a low molecular weight diol component maybe together used, examples thereof including aromatic diols (such asbisphenol A, bishydroxyethyl terephthalate, catechol, resorcinol,hydroquinone, and 1,3- or 1,4-xylylenediol; and mixtures thereof); andalicyclic diols (such as hydrogenated bisphenol A, xylylenediol,cyclohexanediol, and cyclohexanedimethanol). Furthermore, as the needarises, a polyol component having a tri- or higher functionality may betogether used, examples thereof including glycerin, trimethylolethane,trimethylolpropane, polyesterpolyol, polycarbonatepolyol, andpolyetherpolyol. Such polyol components preferably contain at least aC₂₋₈ polyol component (in particular, a C₂₋₆ alkylene glycol). Theproportion of the C₂₋₈ polyol component (in particular, the C₂₋₆alkylene glycol) in 100% by mass of the polyol component(s) may beselected from the range of about 50 to 100% by mass, and usually, theproportion is preferably from 70% by mass to 100% by mass, morepreferably from 80% by mass to 100% by mass, even more preferably from90% by mass to 100% by mass.

In the present invention, from the viewpoint of improvement in the gasbarrier performance by forming of the crystalline portions deriving fromurethane bonds, it is more preferred to use a urethane resin containing,as a main constituent component, an aromatic or aromatic-aliphaticdiisocyanate component. It is particularly preferred that the urethaneresin contains, out of such diisocyanate components, a m-xylylenediisocyanate component. The use of this resin allows that an effect ofstacking between its aromatic rings heightens the cohesive force of theurethane bonds further. Consequently, the laminated film gains a goodgas barrier performance. The proportion of the aromatic oraromatic-aliphatic diisocyanate in the urethane resin is preferably setto be within a range of 30% by mole or more (30 to 100% by mole) in 100%by mole of the polyisocyanate component (E). The total proportion of thearomatic or aromatic-aliphatic diisocyanate(s) is preferably from 40 to100% by mole, more preferably from 50 to 100% by mole, even morepreferably from 60 to 100% by mole. Such resins are preferably “TAKELAC(registered trademark)” series commercially available from MitsuiChemicals, Inc. If the total proportion of the aromatic oraromatic-aliphatic diisocyanate(s) is less than 30% by mole, thelaminated film may not gain a good gas barrier performance.

The urethane resin preferably has a carboxylate group (carboxyl group)from the viewpoint of an improvement of the protective layer in affinitywith the inorganic thin-film layer. In order to incorporate acarboxylate (salt) into the urethane resin, it is advisable to introducethereinto the following, for example, as a polyol component: a polyolcompound having a carboxylate group, such as dimethylolpropionic acid ordimethylolbutanoic acid, as a copolymerizable component. Moreover, whena carboxylate-group-containing urethane resin is synthesized andsubsequently the reaction system is neutralized with a salt-formingagent, a urethane resin of a water-dispersible product can be gained.Specific examples of the salt-forming agent include ammonia,trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine,tri-n-butylamine, and other trialkylamines; N-methylmorpholine,N-ethylmorpholine, and other N-alkylmorpholines; andN-dimethylethanolamine, N-diethylethanolamine, and otherN-dialkylalkanolamines. These compounds may be used alone or incombination of two or more thereof.

(Properties of Urethane Resin)

The acid value of the urethane resin ranges preferably from 10 to 60mgKOH/g, more preferably from 15 to 55 mgKOH/g, even more preferablyfrom 20 to 50 mgKOH/g. When the acid value of the urethane resin is inany one of these ranges, the resin is improved in liquid stability whenmade into a water-dispersible liquid. Moreover, the resultant protectivelayer can be evenly deposited onto the metal oxide layer having a highpolarity, so that the external appearance of the coat becomes good.

The glass transition temperature (Tg) of the urethane resin in thepresent invention is preferably 100° C. or higher, more preferably 110°C. or higher, even more preferably 120° C. or higher. When the Tg is setto be 100° C. or higher, the surface hardness of the film can be easilyadjusted to be within the aforementioned predetermined range.

As the need arises, the urethane resin of the present invention may beblended with various types of additives within a range that does notdeteriorate the gas barrier performance. Examples of the additivesinclude a silane coupling agent, a layered inorganic compound, astabilizer (an antioxidant, a thermal stabilizer, an ultravioletabsorber, or the like), a plasticizer, an antistatic agent, a lubricant,an anti-blocking agent, a colorant, a filler, and a crystal nucleatingagent.

In particular, the silane coupling agent is effective in improving theadhesion of the gas barrier polyurethane resin to the metal oxide layer.Examples of the silane coupling agent include hydrolyzable alkoxysilanecompounds such as halogen-containing alkoxysilanes(2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane,3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, and otherchloroC2-4alkyltriC1-4alkoxysilanes), alkoxysilanes having an epoxygroup [2-glycidyloxyethyltrimethoxysilane,2-glycidyloxyethyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane,3-glycidyloxypropyltriethoxysilane, and otherglycidyloxyC2-4alkyltriC1-4alkoxysilanes,3-glycidyloxypropylmethyldimethoxysilane,3-glycidyloxypropylmethyldiethoxysilane, and otherglycidyloxyC2-4alkyldiC1-4alkoxysilanes,2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,2-(3,4-epoxycyclohexyl)ethyltriethoxysilane,3-(3,4-epoxycyclohexyl)propyltrimethoxysilane, and other(epoxycycloalkyl)C2-4alkyltriC1-4alkoxysilanes], alkoxysilanes having anamino group [2-aminoethyltrimethoxysilane,3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and otheraminoC2-4alkyltriC1-4alkoxysilanes, 3-aminopropylmethyldimethoxysilane,3-aminopropylmethyldiethoxysilane, and otheraminodiC2-4alkyldiC1-4alkoxysilanes,2-[N-(2-aminoethyl)amino]ethyltrimethoxysilane,3-[N-(2-aminoethyl)amino]propyltrimethoxysilane,3-[N-(2-aminoethyl)amino]propyltriethoxysilane, and other(2-aminoC2-4alkyl)aminoC2-4alkyltriC1-4alkoxysilanes,3-[N-(2-aminoethyl)amino]propylmethyldimethoxysilane,3-[N-(2-aminoethyl)amino]propylmethyldiethoxysilane, and other(aminoC2-4alkyl)aminodiC2-4alkyldiC1-4alkoxysilanes], alkoxysilaneshaving a mercapto group (2-mercaptoethyltrimethoxysilane,3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, andother mercaptoC2-4alkyltriC1-4alkoxysilanes,3-mercaptopropylmethyldimethoxysilane,3-mercaptopropylmethyldiethoxysilane, and othermercaptodiC2-4alkyldiC1-4alkoxysilanes), alkoxysilanes having a vinylgroup (vinyltrimethoxysilane, vinyltriethoxysilane, and othervinyltriC1-4alkoxysilanes), and alkoxysilanes having an ethylenicunsaturated bond group [2-(meth)acryloxyethyltrimethoxysilane,2-(meth)acryloxyethyltriethoxysilane,3-(meth)acryloxypropyltrimethoxysilane,3-(meth)acryloxypropyltriethoxysilane, and other(meth)acryloxyC2-4alkyltriC1-4alkoxysilanes,3-(meth)acryloxypropylmethyldimethoxysilane,3-(meth)acryloxypropylmethyldiethoxysilane, and other(meth)acryloxydiC2-4alkyldiC1-4alkoxysilanes). These silane couplingagents may be used alone or in combination of two or more thereof.

The proportion of the silane coupling agent is 30 parts by weight orless (for example, 0.1 to 30 parts by weight), preferably 0.5 to 20parts by weight, even more preferably about 1 to 10 parts by weight withrespect to 100 parts by weight of the polyurethane resin.

When the protective layer is formed with a resin composition forprotective layer, a coating liquid (application liquid) made of thepolyurethane resin, ion-exchange water, and a water-soluble organicsolvent may be prepared and applied onto the substrate film, followed bydrying. As the water-soluble organic solvent, it is possible to use asingle or mixed solvent selected from alcohols such as ethanol andisopropyl alcohol (IPA), ketones such as acetone and methyl ethylketone, and the like. From the viewpoint of coating film processing andodor, IPA is preferable.

A method for coating with the resin composition for protective layer isnot particularly limited as long as a layer is formed by coating thefilm surface. For example, a usual coating method such as gravurecoating, reverse roll coating, wire bar coating, or die coating can beadopted. From the viewpoint of productivity and coating stability, wirebar coating and gravure coating are suitably used.

In forming the protective layer, heating and drying are preferablycarried out after the resin composition for protective layer is applied.The drying temperature at that time is preferably 110 to 210° C., morepreferably 115 to 205° C., even more preferably 120 to 200° C. When thedrying temperature is lower than 110° C., insufficient drying orinsufficient cohesion by heat is generated in the protective layer,raising a fear that the surface hardness may go out of the predeterminedrange. This may raise a fear that the adhesion and the water resistanceof the protective layer when the retorting treatment is carried out maydecrease. On the other hand, when the drying temperature is higher than210° C., the cohesion of the protective layer proceeds too much, raisinga fear that the film may become too hard, or the resin may be fused tobecome even, making it impossible to obtain a surface unevenness. Also,too much heat may be applied to the film itself which is the substrate,raising a fear that the film may become brittle or the processabilitymay become aggravated by shrinkage. Here, besides the drying, it iseffective to apply an additional heat treatment (for example, 150 to190° C.) in view of allowing the drying of the protective layer toproceed.

According to the above, the laminated film of the present invention is agas barrier laminated film (laminated body) which is excellent in oxygengas barrier performance and interlayer adhesion in an ordinary state andafter being subjected to heat-moisture treatment, has a good adhesionwhen processing such as printing or lamination is carried out, is easyto produce, and is excellent in economy as well.

[Other Layers]

In an inorganic-thin-film-layer-including gas barrier laminated film inwhich the laminated film of the present invention is used, variouslayers that a known gas barrier laminated film has may be optionallylaid besides the above-defined substrate film, coating layer, inorganicthin-film layer and protective layer.

In the case of using the inorganic-thin-film-layer-including gas barrierlaminated film as a packaging material, it is preferred to form aheat-sealable resin layer called a sealant. The heat-sealable resinlayer is usually laid on the inorganic thin-film layer. However, thisresin layer may be laid on the outside of the substrate film (a surfaceof the laminated film that is opposite to the coating-layer-formedsurface thereof). The formation of the heat-sealable resin layer isusually attained by an extrusion laminating method or dry laminatingmethod. A thermoplastic polymer which forms the heat-sealable resinlayer is any thermoplastic resin as far as the resin can sufficientlyexpress sealant adhesion. Examples thereof include polyethylene resinssuch as HDPE, LDPE, and LLDPE, polypropylene resin, ethylene-vinylacetate copolymer, ethylene-α-olefin random copolymer, and ionomerresin.

Furthermore, in the inorganic-thin-film-layer-including gas barrierlaminated film, one or more printed layers, and one or more differentplastic substrates and/or paper substrates may be laminated, in a layerform, into between the inorganic thin-film layer or the substrate film,and the heat-sealable resin layer, or onto the outside thereof.

A printing ink for forming the printed layer is preferably a water basedor solvent based resin-containing printing ink. Examples of a resin usedin the printing ink include acrylic resin, urethane-based resin,polyester-based resin, vinyl chloride-based resin, and vinyl acetatecopolymer resin; and a mixture of two or more of these resins. Theprinting ink may contain known additives, such as antistatic agents,light blocking agents, ultraviolet absorbers, plasticizers, lubricants,fillers, colorants, stabilizers, lubricants, antifoaming agents,crosslinking agents, anti-blocking agents, and antioxidants. Theprinting method for laying the printed layer is not particularlylimited, and a known method may be used, examples thereof including anoffset printing method, a gravure printing method, and a screen printingmethod. The drying of the solvent after the printing may be a knowndrying method such as hot wind drying, hot roll drying, or infrareddrying.

For the different plastic substrate(s) or paper substrate(s), forexample, the following are preferably used to give a sufficient rigidityand strength to the laminated body: paper, polyester resin, polyamideresin, and biodegradable resin. In order to produce a film excellent inmechanical strength, it is preferred to use a drawn film, such as abiaxially drawn polyester film or a biaxially drawn nylon film.

In the case of using, particularly as a packaging material, theinorganic-thin-film-layer-including gas barrier laminated film, it ispreferred to laminate a nylon film into between the inorganic thin-filmlayer and the heat-sealable resin layer to improve the film inmechanical properties such as pinhole resistance and piercing strength.The species of the nylon may be usually, for example, nylon 6, nylon 66,or m-xylyleneadipamide. The thickness of the nylon film is usually from10 to 30 μm, preferably from 15 to 25 μm. If the nylon film is thinnerthan 10 μm, the film may be unfavorably short in strength. In themeantime, if the thickness is more than 30 μm, the film is large infirmness and flexibility to be unsuitable for being worked. The nylonfilm is preferably a biaxially drawn film about which the draw ratio ineach of the longitudinal and lateral directions is usually 2 or more,preferably from 2.5 to 4.

The laminated film of the present invention also includes embodimentseach having one or more of the above-mentioned various layers other thanthe coating layer and the inorganic thin-film layer.

EXAMPLES

Hereinafter, the present invention will be more specifically describedby way of working examples thereof. However, the invention is notlimited by the working examples. The working examples may be carried outin the state that an appropriate modification may be applied thereto asfar as the modified forms can conform to the subject matters of theinvention, which have been described above or will be described later.These modified forms are each included in the technical scope of theinvention. Unless otherwise specified, the symbol “%” and the word“part(s)” denote “% by mass” and “part(s) by mass”, respectively.

Evaluating methods and physical property measuring methods that wereused in each of the working examples and comparative examples are asfollows:

(1) Production of Laminated Bodies for Evaluations

By the dry laminating method, an undrawn polypropylene film (“P1147”,manufactured by Toyobo Co., Ltd.) as a heat-sealable resin layer, whichhad a thickness of 70 μm, was bonded onto a protective layer surfaceside (vapor-deposited layer surface side when the protective layer wasabsent) of each of laminated films yielded in each of the workingExamples and the Comparative Examples through a urethane basedtwo-liquid-component curable adhesive (in which a product “TAKELAC(registered trademark) A525S” manufactured by Mitsui Chemicals, Inc. anda product “TAKENATE (registered trademark) A50” manufactured by thesame) were blended with each other at a ratio (by mass) of 13.5:1). Theresultant was aged at 40° C. for 4 days. Thus, in each of the examples,laminate-gas-barrier laminated bodies for evaluation (hereinafterreferred to also as “laminated bodies”) were yielded. The thickness ofan adhesive layer made from the urethane based two-liquid-componentcurable adhesive was adjusted to be one of two types of about 2 μm andabout 5 μm by changing the concentration after the adhesive was dried.

(2) Method for Evaluating Oxygen Permeability

In accordance with the electrolytic sensor method in JIS-K7126-2(Appendix A), an oxygen permeability measuring instrument (“OX-TRAN2/20”, manufactured by MOCON Inc.) was used to measure the oxygenpermeability of a simple member that was another laminated film yieldedin each of the examples, in a usual state of the film, in an atmosphereof 23° C. temperature and 65% relative humidity. The measurement of theoxygen permeability was made in a direction in which oxygen permeatesthe film from the substrate film side thereof, on which no coatinglayer/protective layer was laminated, to the coating layer/protectivelayer side thereof.

Separately, one of the laminated bodies produced in each of the examplesin the item (1) was subjected to heat-moisture treatment for keeping thelaminated body in hot water of 130° C. temperature for 30 minutes, andthen dried at 40° C. for 1 day (24 hours). About the resultant laminatedbody subjected to the heat-moisture treatment, the oxygen permeabilitythereof was measured (after the body was retorted) in the same way asdescribed above.

(3) Method for Evaluating Laminate Strength

One of the laminated bodies produced in each of the examples in the item(1) was subjected to a heat-moisture treatment for keeping the laminatedbody in hot water of 130° C. temperature for 30 minutes, and was cut outin an undried state into a test piece of 15 mm width and 200 mm length.A Tensilon universal material test machine (“TENSILON, UMT-II-500model”, manufactured by Toyo Baldwin Co., Ltd.) was used to measure thelaminate strength thereof (after the piece was retorted) underconditions with a temperature of 23° C. and a relative humidity of 65%.The laminate strength was defined as the strength of the test piece whenthe piece was subjected to a peeling treatment at a peeling rate of 200mm/minute and at a peeling angle of 90 degrees.

(4) Method for Measuring Arithmetic Mean Roughness of Protective Layer

Measurement of the arithmetic mean roughness of the protective Layer wascarried out with use of a scanning probe microscope (SPM) (“SPM9700”manufactured by Shimadzu Corporation) (cantilever: OMCL-AC200TSavailable from Olympus Corporation was used, observation mode: phasemode). In more details, an SPM image was obtained in a viewing angle of2-μm square on the coating layer surface. In the obtained image,inclination correction, which was a function of a software attached tothe SPM, was used so as to perform inclination correction in the X-, Y-,and Z-directions, and thereafter the value of the arithmetic meanroughness was calculated out.

(5) Method for Measuring Surface Hardness of Protective Layer

Measurement of the surface hardness of the protective layer was carriedout with use of a dynamic ultra-microhardness tester (“DUH-211”manufactured by Shimadzu Corporation). In more details, a diamondtriangular pyramid indenter (Berkovich type) having an intercristalangle of 115° was used on the protective layer surface of a simplemember of the laminated film fixed and held on a glass plate with anadhesive, so as to perform a hardness measurement test by theloading-unloading test, and the obtained martens hardness was regardedas the value of the surface hardness. The test conditions were with atest force of 0.1 mN, a loading rate of 0.02 mN/second, and a holdingtime of 2 seconds.

(6) Method for Evaluating Printing Suitability of Film

A printing layer of 2 μm was laminated on a simple member of the yieldedlaminated film with use of a solvent-based ink (“LIOALPHA (registeredtrademark) R641 white” manufactured by Toyo Ink Co., Ltd.) The yieldedprinting layer was scraped for 5 times with use of a cotton swab. Atthat time, those in which the ink was not peeled off were evaluated ashaving an adhesion with ◯; those in which the ink was partially peeledoff were evaluated as having an adhesion with Δ; and those in which theink was peeled off over the whole surface were evaluated as having anadhesion with X. Also, as to the ink transfer performance, half-toneprinting was carried out at a concentration of 60% with use of theaforementioned ink, and surface observation of the printing layer wascarried out with use of an optical microscope at a magnification of ×50times. At that time, those in which the ink was connected in a net shapewere evaluated as having a transfer performance with ◯; those in whichthe ink was partially disconnected were evaluated as having a transferperformance with Δ; and those in which the ink was not connected at alland had a dotted shape were evaluated as having a transfer performancewith X.

(7) Method for Measuring Adhesion Amount of Protective Layer

In each of the working Examples and the Comparative Examples, alaminated film yielded at a stage when a protective layer was laminatedonto a substrate film was used as a sample. From this sample, a testpiece of 100 mm×100 mm size was cut out. The protective layer was wipedoff with 1-methoxy-2-propanol or dimethylformamide. From a change in themass before and after the wiping-off, the adhesion amount of the layerwas calculated out.

(8) Oxazoline Group Amount of Resin Having Oxazoline Group

A resin containing an oxazoline group was freeze-dried, and then a¹H-NMR spectrum thereof was measured, using a nuclear magnetic resonanceanalyzer (NMR) GEMINI-200, manufactured by Varian Inc. to gain theintensity of an absorption peak originating from the oxazoline group,and that of each of absorption peaks originating from the othermonomers. From these peak intensities, the oxazoline group amount(mmol/g) was calculated out.

(9) Method of Determining Isocyanate Components in Urethane Resin

A sample was dried under reduced pressure, and a ¹H-NMR spectrum thereofwas measured, using a nuclear magnetic resonance analyzer (NMR)GEMINI-200, manufactured by Varian Inc. From the integration ratiobetween the respective peak intensities originating from individualisocyanate components of the sample, the ratio by mole between theisocyanate components was determined.

In each of the working examples, and the comparative examples,individual materials used in its coating layer and its protective layerwere prepared as follows:

<Preparation of Individual Materials Used to Form Coating Layer orProtective Layer> [Resin (A) Having Oxazoline Group]

As a resin having an oxazoline group, a commercially availablewater-soluble oxazoline-group-containing acrylate was prepared (“EPOCROS(registered trademark) WS-300”, manufactured by Nippon Shokubai Co.,Ltd.; solid content: 10%). The oxazoline group amount in this resin was7.7 mmol/g.

[Acrylic Resin (B)]

As an acrylic resin, a commercially available acrylate copolymeremulsion having a concentration of 25% by mass was prepared (“MOVINYL(registered trademark) 7980”, manufactured by Nichigo-Movinyl Co. Ltd.).This acrylic resin (B) had an acid value (theoretical value) of 4mgKOH/g.

[Urethane Resin (C)]

As a urethane resin, a commercially available polyester urethane resindispersion was prepared (“TAKELAC (registered trademark) W605”,manufactured by Mitsui Chemicals, Inc.: solid content: 30%). Thisurethane resin had an acid value of 25 mgKOH/g, and a glass transitiontemperature (Tg) of 100° C., which was measured by DSC. The proportionof its aromatic or aromatic-aliphatic diisocyanates was 55% by mole ofthe whole of its polyisocyanate components, the proportion beingmeasured by ¹H-NMR.

[Urethane Resin (D1)]

As a urethane resin, a commercially availablem-xylylene-group-containing urethane resin dispersion was prepared(“TAKELAC (registered trademark) WPB341”, manufactured by MitsuiChemicals, Inc.; solid content: 30%). This urethane resin had an acidvalue of 25 mgKOH/g, and a glass transition temperature (Tg) of 130° C.,which was measured by DSC. The proportion of its aromatic oraromatic-aliphatic diisocyanates was 85% by mole of the whole of itspolyisocyanate components, the proportion being measured by ¹H-NMR.

[Urethane Resin (D2)]

As a urethane resin, a commercially available polycarbonate urethaneresin dispersion was prepared (“TAKELAC (registered trademark) WS4000”,manufactured by Mitsui Chemicals, Inc.: solid content: 30%). Thisurethane resin had a glass transition temperature (Tg) of 130° C., whichwas measured by DSC.

[Urethane Resin (D3)]

As a urethane resin, a commercially available polyester urethane resindispersion was prepared (“TAKELAC (registered trademark) WS4022”,manufactured by Mitsui Chemicals, Inc.; solid content: 30%). Thisurethane resin had a glass transition temperature (Tg) of 110° C., whichwas measured by DSC.

[Silane Coupling Agent (G)]

As a silane coupling agent, a commercially available “(registeredtrademark) KBM603”; solid content: 30%) manufactured by Shin-EtsuChemical Co., Ltd. was prepared. [Gas Barrier Vinyl Alcohol Resin (H)]

As a vinyl alcohol-based resin having gas barrier performance, acommercially available water-soluble vinyl alcohol resin (“NichigoG-Polymer (registered trademark) OKS-8049”, manufactured by The NipponSynthetic Chemical Industry Co., Ltd.; powder) was dissolved into waterto prepare an aqueous solution thereof having a solid content of 5%.

[Gas Barrier Protective Layer Solution (I)]

A solution yielded by hydrolyzing tetraethoxysilane with 0.02 mol/L ofhydrochloric acid was added into a 5%-by-weight aqueous solution ofpolyvinyl alcohol resin (PVA) having a saponification degree of 99% anda polymerization degree of 2400 so as to attain a proportion ofSiO2/PVA=60/40 in weight ratio, as a gas barrier protective layersolution (I).

Example 1 (1) Preparation of Coating Liquid 1 Used in Coating Layer

Individual materials each having a blend proportion described below weremixed with each other to produce a coating liquid (resin composition forcoating layer). In the resultant coating liquid, the ratio by massbetween the oxazoline-group-having resin (A), the acrylic resin (B) andthe urethane resin (C), this ratio being a ratio in terms of solidcontents in the liquid, was as shown in Table 1.

Water: 54.40%,

Isopropanol: 25.00%,

Oxazoline-group-containing resin (A): 15.00%,

Acrylic resin (B): 3.60%, and

Urethane resin (C): 2.00%.

(2) Preparation of Coating Liquid 2 Used in Coating of Protective Layer

Coating agents described below were mixed with each other to produce acoating liquid 2. The proportion by mass of the urethane resin (D1),this proportion being a proportion in terms of a solid content in thecoating liquid, was as shown in Table 1.

Water: 58.33%,

Isopropanol: 30.00%, and

Urethane resin (D1): 11.67%.

(3) Production of Polyester Substrate Film, and Coating with CoatingLiquid 1 (Lamination of Coating Layer)

(4) Formation (Vapor Deposition) of Inorganic Thin-Film Layer

Next, by an electron beam vapor deposition method, an inorganic complexoxide layer made of silicon dioxide and aluminum oxide was formed, as aninorganic thin-film layer, onto the coating layer surface of thelaminated film yielded in the item (2). A used vapor deposition sourcewas SiO₂ (purity: 99.9%) and Al₂O₃ (purity: 99.9%) in the form ofparticles having a size of about 3 to 5 mm. The composition of thecomplex oxide layer was as follows: SiO₂/Al₂O₃ (ratio by mass)=60/40.The film thickness of the inorganic thin-film layer (SiO₂/Al₂O₃ complexoxide layer) was 13 nm.

(5) Coating with Coating Liquid 2 onto Vapor-Deposited Film (Laminationof Protective Layer)

The upper of the inorganic thin-film layer of the vapor-deposited filmyielded in the item (4) was coated with the coating liquid 2 by the wirebar coating method, and this workpiece was dried at 200° C. for 15seconds to yield a protective layer. The coat amount of the layer afterthe drying was 0.210 g/m² (Dry).

As described above, each laminated film was produced in which thecoating layer/the metal oxide layer/the protective layer were formed onthe substrate film. About the resultant laminated film, the oxygenpermeability, the laminate strength, and the printing performance wereevaluated as described above. The results are shown in Table 1.

Examples 2 to 7 and Comparative Examples 1 to 6

In each of the Examples 2 to 7 and Comparative Examples 1 to 6, eachlaminated film was produced in the same way as in Example 1 except that:in the preparation of the coating liquid for forming the protectivelayer, the blending amount, the adhesion amount and the species of theresins were changed as shown in Table 1. The oxygen permeability, thelaminate strength, and the printing performance thereof were evaluated.The results are shown in Table 1.

Protective layer Coating layer (upper row: resin name, Oxazoline- lowerrow: mass % ratio) group- A/B/C (D1)/ Adhesion containing AcrylicUrethane [ratio by (D1) (G) (D2) (D3) (H) (I) (B) amount resin resinresin mass] 100 99/1 100 100 100 100 100 [g/m²] Example 1 (A) (B) (C)50/30/20 ○ — — — — — — 0.21 Example 2 (A) (B) (C) 50/30/20 ○ — — — — — —0.30 Example 3 (A) (B) (C) 50/30/20 — ○ — — — — — 0.45 Example 4 (A) (B)(C) 50/30/20 — — ○ — — — — 0.45 Example 5 (A) (B) (C) 40/50/10 ○ — — — —— — 0.45 Example 6 (A) (B) (C) 30/50/20 ○ — — — — — — 0.45 Example 7 (A)— — 100/0/0 ○ — — — — — — 0.45 Comparative — — — — ○ — — — — — — 0.45Example 1 Comparative (A) (B) (C) 50/30/20 — — — — — — — — Example 2Comparative (A) (B) (C) 50/30/20 — — — ○ — — — 0.45 Example 3Comparative (A) (B) (C) 50/30/20 — — — — ○ — — 0.45 Example 4Comparative (A) (B) (C) 50/30/20 — — — — — ○ — 0.45 Example 5Comparative (A) (B) (C) 50/30/20 — — — — ○ 0.45 Example 6 Evaluationitems Laminate strength after retorting Oxygen [N/15 mm] PrintingArithmetic permeability Thickness Thickness suitability mean Surface[ml/m² · day · MPa] of of Ink roughness hardness Before After adhesiveadhesive transfer [nm] [N/mm2] retorting retorting 2 μm 5 μm Adhesionperformance Example 1 0.82 448 1.9 1.9 2.9 2.4 ○ ○ Example 2 0.69 4521.9 1.9 2.9 2.4 ○ ○ Example 3 0.70 405 2.0 2.0 4.2 4.2 ○ ○ Example 41.47 434 7.9 7.9 2.7 2.9 ○ ○ Example 5 1.46 449 1.9 2.0 2.8 2.7 ○ ○Example 6 1.44 453 1.8 2.0 2.7 2.6 ○ ○ Example 7 1.55 440 2.0 3.2 2.72.9 ○ ○ Comparative 0.68 471 2.0 11 1.6 1.6 ○ ○ Example 1 Comparative3.00 317 20 20 2.9 2.9 Δ ○ Example 2 Comparative 1.01 225 8.1 8.1 3.74.3 ○ × Example 3 Comparative 0.33 440 1.0 3.5 0  0  ○ ○ Example 4Comparative 0.24 728 2 10 1.5 3.8 Δ ○ Example 5 Comparative 0.41 340 8.312 1.1 1.5 ○ Δ Example 6

INDUSTRIAL APPLICABILITY

The present invention allows to provide a gas barrier laminated filmhaving an inorganic thin-film layer, which is excellent in gas barrierperformance and simultaneously excellent in adhesion irrespective of thethickness of the adhesive and further has a sufficient adhesion andtransfer performance to an ink at the time of printing, of course, inthe state that the film is kept in an ordinary state, and also after thefilm is subjected to a heat-moisture treatment. This gas barrierlaminated film has advantages of being easily produced, being excellentin economy and production stability, and gaining even properties easily.Also, since this gas barrier laminated film has an excellent adhesion,the thickness of the adhesive can be reduced, thereby largelycontributing to safety and hygiene at the time of processing and toeconomy (costs). Accordingly, this gas barrier laminated film is widelyusable not only for food packaging for a heat-moisture treatment, butalso for the packaging of various foods, medicines, industrial productsand other products, and for industrial articles such as solar batteries,electronic paper, organic EL elements, semiconductor elements, andothers.

1. A laminated film comprising a substrate film and a coating layer thatis disposed on/over at least one surface of the substrate film; thecoating layer comprising a resin composition for coating layer,comprising, as a constituent component, a resin having an oxazolinegroup; the laminated film having an inorganic thin-film layer on/overthe coating layer, and further having a protective layer that has aurethane resin on/over the inorganic thin-film layer; the protectivelayer of the laminated film having a surface hardness of 350 to 700N/mm²; and the protective layer having an arithmetic mean roughness of0.5 to 2.0 nm in a 2-μm square.
 2. The laminated film according to claim1, wherein the urethane resin comprised in the protective layercomprises an aromatic or aromatic-aliphatic component.
 3. The laminatedfilm according to claim 2, wherein the urethane resin comprised in theprotective layer comprises a m-xylylene component.
 4. The laminated filmaccording to claim 3, wherein the oxazoline-group-containing resin inthe resin composition for coating layer, contains an oxazoline groupamount of 5.1 to 9.0 mmol/g.
 5. The laminated film according to claim 4,wherein the coating layer comprises therein an acrylic resin having anacid value of 10 mgKOH/g or less.
 6. The laminated film according toclaim 5, wherein the inorganic thin-film layer is a layer of a complexoxide of silicon oxide and aluminum oxide.
 7. The laminated filmaccording to claim 1, wherein the urethane resin comprised in theprotective layer comprises a m-xylylene component.
 8. The laminated filmaccording to claim 1, wherein the oxazoline-group-containing resin inthe resin composition for coating layer, contains an oxazoline groupamount of 5.1 to 9.0 mmol/g.
 9. The laminated film according to claim 1,wherein the coating layer comprises therein an acrylic resin having anacid value of 10 mgKOH/g or less.
 10. The laminated film according toclaim 1, wherein the inorganic thin-film layer is a layer of a complexoxide of silicon oxide and aluminum oxide.